The Major League Baseball season has officially hit its quarter poll. That's usually a great signifier on having enough data and playing time to make truly informed decisions as fantasy baseball managers. Any player can hit .380 for the first few weeks of the season. All it takes is a hot start with a little luck on batted balls in play and your numbers can be massively inflated. But now we are more than 40 games into the season. Fantasy baseball managers should be able to know by now the strengths and weaknesses of their teams.

For most people, fantasy baseball is a week to week experience. You want to put your team in the best position possible to beat your opponent each week in head-to-head leagues. With Week 7 beginning Monday with an early Rockies vs. Pirates game at 3:35 eastern time, now is a good time to take a look at some key players to focus on.

Here are our four waiver wire additions for Week 7 of the fantasy baseball season.

Fantasy Baseball: Week 7 Waiver Wire Targets

1. Nick Pivetta – Red Sox SP

A couple of weeks ago I could not have imagined a scenario where I suggest adding Nick Pivetta to fantasy baseball lineups. But here I am. There are a number of reasons for this too.

The most important reason is how well he is pitching right now. Pivetta is coming off a complete game victory. He shut down the vaunted Houston Astros lineup, allowing just one run and striking out eight. But his prior two starts was almost as impressive. Overall, over his last three starts, Pivetta is 2-0 with three quality starts, 20 strikeouts, allowing a total of two runs and an insane 11 total baserunners over 22 innings. Okay, so he is pitching lights out. It was against solid competition too in the aforementioned Astros, the White Sox and in Arlington at the Rangers. Yes, Texas does not have a good offense but it's not easy to dominate in that ball park.

The schedule is the next reason. Pivetta's next start will come Tuesday against the White Sox again. His two starts after that will be at home against the Orioles and at the Athletics.

Finally, Boston's offense is coming to life. The team as a whole has now won five straight games, scoring 38 runs during the winning streak.

All of this points to Pivetta continuing to be fantasy baseball worthy. You will likely drop him at some point this season, but for now, he's worth an add.

2. Emmanuel Rivera – Royals 3B

The Royals rookie third baseman, Emmanuel Rivera, is quietly showing that he belongs in the big leagues. Most fantasy baseball managers have not noticed as of yet, as seen by his 2 percent rostered rate in Yahoo leagues. But there is a clear path to playing time and he is making the best of it.

Through his first 19 big league games, Rivera has three home runs, nine runs scored and nine RBI. He continues to receive everyday at-bats in the Royals lineup. He has never really shown much power at the minor league level, nor does he offer much speed. But he generally has been a decent singles and doubles hitter. While he's going well, he's worth a speculative add in fantasy baseball leagues.

3. Luis Arraez – Twins 1B, 2B, 3B, OF

Obviously, just by looking next to his name above, you can see the potential inherent value. Luis Arraez qualifies at first base, second base, third base and outfield. That flexibility is always nice to have, especially early in the baseball season when so many games get postponed due to weather.

But he offers more than just positional flexibility.

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Arraez has quietly been the engine that lights the Twins offense. He's been hitting atop the lineup of the AL Central leading Minnesota Twins. Despite lacking for both power and speed, he has proven he can consistently hit for average. He's a career .314 hitter with a .380 on-base percentage. That's not off a small sample size either. He has over 1,000 career plate appearances.

He's also been hitting especially well of late. Arraez has 12 hits over his last 28 at-bats with nine runs scored. His rostered percentage is surely to spike after this week, so fantasy managers be aware, you were warned.

4. Harrison Bader – Cardinals OF

It's somewhat mystifying how Harrison Bader has lasted this long on the majority of fantasy baseball waiver wires. All he does is produce. He's given fantasy baseball managers top-100 production this season in 5×5 mixed leagues and has shown in the past that it's not a fluke.

Last year in just 103 games, Bader hit 16 home runs and stole nine bases. But this year, he clearly is taking the training wheels off. Bader is already up to 11 stolen bases. So, if you are looking for some cheap speed, he's your guy. Even though you might not get a ton of production elsewhere, this type of base stealing is hard to come by.